Penetration and distribution of alpha-tocopherol, alpha- or gamma-tocotrienols applied individually onto murine skin.
To evaluate skin penetration of various vitamin E homologs, a 5% solution of either alpha-tocopherol, alpha-tocotrienol, or gamma-tocotrienol in polyethylene glycol was topically applied to SKH-1 hairless mice. After 0.5, 1, 2, or 4 h (n = four per time point and four per vitamin E homolog), the skin was washed, the animals killed, the skin rapidly removed, frozen on dry ice, and a biopsy taken and sectioned: stratum corneum (two uppermost, 5-micron sections--SC1 and SC2), epidermis (next two 10-micron sections--E1 and E2), papillary dermis (next 100 microns, PD), dermis (next 400 microns, D), and subcutaneous fat (next 100 microns, SF). SC1 contained the highest vitamin E concentrations per mu thickness. To compare the distribution of the various vitamin E forms into the skin layers, the percentage of each form was expressed per its respective total. Most surprising was that the largest fraction of skin vitamin E following topical application was found in the deeper subcutaneous layers--the lowest layers, PD (40 +/- 15%) and D (36 +/- 15%), contained the major portion of the applied vitamin E forms. Although PD only represents about 16% of the total skin thickness, it contains sebaceous glands--lipid secretory organs, and, thus, may account for the vitamin E affinity for this layer. Hence, applied vitamin E penetrates rapidly through the skin, but the highest concentrations are found in the uppermost 5 microns.
Traber
M G
MG
Department of Molecular and Cell Biology, University of California, Berkeley 94720-3200, USA. mgtraber@uclink4.berkeley.edu
Rallis
M
M
Podda
M
M
Weber
C
C
Maibach
H I
HI
Packer
L
L
D000287:Administration, Topical; D000818:Animals; D002839:Chromans / Q000008:administration & dosage / Q000493:pharmacokinetics*; D005260:Female; D007700:Kinetics; D051379:Mice; D008812:Mice, Hairless; D011092:Polyethylene Glycols; D012867:Skin / Q000378:metabolism*; D012996:Solutions; D014018:Tissue Distribution; D024508:Tocotrienols; D014810:Vitamin E / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000493:pharmacokinetics*
D002839:Chromans; D012996:Solutions; D024508:Tocotrienols; D014810:Vitamin E; D011092:Polyethylene Glycols; C013649:plastochromanol 8; C082032:tocotrienol, alpha